Optical properties of GaN nanowires grown on chemical vapor deposited-graphene.

Optical properties of GaN nanowires (NWs) grown on chemical vapor deposited-graphene transferred on an amorphous support are reported. The growth temperature was optimized to achieve a high NW density with a perfect selectivity with respect to a SiO2 surface. The growth temperature window was found to be rather narrow (815°C ± 5°C). Steady-state and time-resolved photoluminescence from GaN NWs grown on graphene was compared with the results for GaN NWs grown on conventional substrates within the same molecular beam epitaxy reactor showing a comparable optical quality for different substrates. Growth at temperatures above 820 °C led to a strong NW density reduction accompanied with a diameter narrowing. This morphology change leads to a spectral blueshift of the donor-bound exciton emission line due to either surface stress or dielectric confinement. Graphene multi-layered micro-domains were explored as a way to arrange GaN NWs in a hollow hexagonal pattern. The NWs grown on these domains show a luminescence spectral linewidth as low as 0.28 meV (close to the set-up resolution limit).

Spin-Momentum Locking and Ultrafast Spin-Charge Conversion in Ultrathin Epitaxial Bi1 - x Sbx Topological Insulator.

The helicity of three-dimensional (3D) topological insulator surface states has drawn significant attention in spintronics owing to spin-momentum locking where the carriers' spin is oriented perpendicular to their momentum. This property can provide an efficient method to convert charge currents into spin currents, and vice-versa, through the Rashba-Edelstein effect. However, experimental signatures of these surface states to the spin-charge conversion are extremely difficult to disentangle from bulk state contributions. Here, spin- and angle-resolved photo-emission spectroscopy, and time-resolved THz emission spectroscopy are combined to categorically demonstrate that spin-charge conversion arises mainly from the surface state in Bi1 - x Sbx ultrathin films, down to few nanometers where confinement effects emerge. This large conversion efficiency is correlated, typically at the level of the bulk spin Hall effect from heavy metals, to the complex Fermi surface obtained from theoretical calculations of the inverse Rashba-Edelstein response. Both surface state robustness and sizeable conversion efficiency in epitaxial Bi1 - x Sbx thin films bring new perspectives for ultra-low power magnetic random-access memories and broadband THz generation.

Switching to etanercept in patients with rheumatoid arthritis with no response to infliximab.

TNF-alpha is thought to play a pivotal role in the initiation and perpetuation of the chronic inflammatory process in rheumatoid arthritis. TNF-alpha blockers such as infliximab and etanercept are currently used in the treatment of active rheumatoid arthritis (RA) when traditional DMARDs have failed and are effective in a significant proportion of patients. However, about one third are non-responders to anti-TNF-alpha. The aim of this study was to verify whether rheumatoid patients, after failing infliximab, can benefit from etanercept. We analysed 18 patients with active RA with no response to at least 3 DMARDs and where infliximab therapy had failed. The patients had received infliximab associated with methotrexate: eleven of them did not show any significant response, while seven patients, after a good response, relapsed. Etanercept was then started. EULAR criteria of response were used with calculation of activity index DAS28 at baseline, after 2 weeks, 3 months and every third month until last follow-up. A moderate or good response was achieved with etanercept in 13 out of 18 patients. From our experience, etanercept can be considered as a good alternative choice when infliximab has failed.

[Prevalence and aggressiveness of thyroid carcinoma with diameter less than one centimetre in iodine deficiency areas]. / Prevalenza ed aggressività del carcinoma tiroideo nei noduli con diametro inferiore al centimetro in aree iodio carenti.

BACKGROUND: The introduction of highly sensitive imaging techniques has made it possible to detect many non-palpable thyroid nodules with size less than 1 centimetre. The prevalence of these lesions appears to be high in the general population and increases in iodine deficiency areas. Fine needle aspiration biopsy (FNAB) is considered the most reliable test for the diagnosis of thyroid nodules. METHODS: From January 1991 to December 2000, 6627 nodules were referred for FNAB to our department. In 4871 (73.5%) euthyroid patients the mean daily urinary excretion of iodine was 73+/-18 micromg/day. RESULTS: In 2401 nodules (36.2%) the diameter was less than one centimetre. Histologic confirmation of malignancy was available in 187 (89.9%) of 208 operated nodules with diameter more than 1 cm and in 64 (78%) of 82 with diameter less than 1 cm. Logistic regression analysis indicated that a solid hypoechoic feature was a useful criterion to predict malignancy (p<0.001), as well as the presence of calcification (p<0.5) and blurred margins (p<0.5). Lymph node metastases were present in 24.3% of carcinomas with diameter more than 1 cm but, surprisingly, also in 20.3% of those with diameter less than 1 cm. No correlation was seen between diameter of carcinoma nodules and presence of lymph node metastasis. CONCLUSIONS: These data suggest that the potential malignancy of thyroid nodules is not only correlated to the diameter but to other parameters such as the biological difference of thyroid cancer that could be hypothesized in an iodine deficiency area. In conclusion, FNAB is recommended for nodules with diameter less than 1 centimetre when sonographic findings suggest malignancy such as a hypoechoic pattern, an irregular margin or internal microcalcification.

[Melanoma metastatic to the trachea and nasal cavity: description of a case and review of the literature]. / Melanoma metastatico alla trachea e alla cavità nasa-le: descrizione di un caso e revisione della letteratura.

Secondary tumors of the trachea are exceedingly rare, only 14 cases having been reported in the literature. Moreover, metastatic involvement of naso-paranasal cavities can be considered quite unusual. Approximately 150 cases have been drawn from the literature, most of which presented a metastatic deposit from a renal adenocarcinoma. Report is then made of a case of cutaneous melanoma metastatic to the trachea and nasal cavity. The tracheal lesion was repeatedly treated with Nd Yag laser, whereas no treatment was considered eligible for nasal metastasis. The patient succumbed to the tumor 16 months after diagnosis of tracheal involvement had been made. The tendency for malignant melanomas to metastasize to distant organs via the bloodstream is well known, yet trachea and nasoparanasal involvement by metastatic melanoma has been reported, respectively, in only three and six cases, including the present one. Prognosis is unfavorable due to the unusual coexistence of metastases to other organs and the lack of an adequate treatment.

A Case of Concurrent Riedel's, Hashimoto's and Acute Suppurative Thyroiditis.

Riedel's thyroiditis (RT) is a rare form of infiltrative and inflammatory disease of the thyroid, first described by Bernard Riedel in 1896. The concurrent presence of RT and other thyroid diseases has been reported, but, the association of RT with Hashimoto's thyroiditis and acute thyroiditis has not yet been reported. We present a case of concurrent Riedel's, Hashimoto's and acute thyroiditis that occurred in a 45-year-old patient.

Usefulness of the scraping method for DNA flow cytometry in breast tumors.

Flow cytometric DNA analysis is an important prognostic tool in breast cancer. We evaluated the possibility of performing DNA analysis on cell suspensions obtained by scraping the cut surface of breast tumors; 31 breast tumor nodules, including six benign and 25 malignant lesions, were studied. From each case, cell suspensions acquired by mechanical mincing of a fresh frozen tissue fragment and by two different scrapings (central and peripheral) from the cut surface of the tumor were analyzed via flow cytometry. In all cases, comparison of the DNA histograms for three samples showed no significant differences in the appearance of debris or in the value of coefficient of variation of the G0-G1 peak. All benign nodules showed a normal DNA stemline in all specimens. In 23 of 25 cases of breast carcinoma, the ploidy of the three preparations was similar, with a concordance in 12/14 (85, 71%) cases in DNA nondiploid tumors. Linear regression analysis showed a good correlation in DNA index between either scraping sample and the tissue fragment (r = .955 and r = .905). The results indicate that the scraping technique provides excellent cell suspensions and DNA histograms comparable to those obtained from mechanical mincing of tissue fragments. The technique minimizes preparation time and avoids consuming much tissue and, thus, is the method of choice when very small cancers have to be analyzed.

bcl-2 expression in pleural and extrapleural solitary fibrous tumours.

This study evaluated the immunoreactivity for bcl-2, a molecule involved in the control of programmed cell death, in cases of pleural (14) and extrapleural (2) solitary fibrous tumour (SFT), malignant mesotheliomas of different histological types, and a variety of extrapleural CD34-positive and CD34-negative spindle-cell tumours. In all SFTs, strong and diffuse immunostaining was demonstrated with anti-bel-2 antibody, sharply contrasting with the complete lack of staining observed in all mesotheliomas. The specificity of immunodetection of bcl-2 in SFT was confirmed by immunoblot analysis, showing a band consistent with the bcl-2 protein. At extrapleural locations, strong bcl-2 immunoreactivity was observed in Schwannoma (2/3 cases), synovial sarcoma (4/4 cases), and all cases of CD34-positive gastrointestinal stromal tumour (GIST; 10/10 cases). Most sarcomas were bcl-2-negative. Lack of bcl-2 expression was demonstrated in tumours which can pose problems in the differential diagnosis of SFT and can exhibit haemangiopericytoma-like features, including haemangiopericytoma (3 cases), dermatofibrosarcoma protuberans (16 cases), and deep-seated fibrous histiocytoma (3 cases). The constitutive expression of bcl-2 in SFT widens the spectrum of available markers for these tumours, providing a useful adjunct to their differential diagnosis in difficult cases at pleural and extrapleural sites, and contributing to the understanding of their histogenesis and molecular pathogenesis.